A variety of different devices have been developed for absorbing the kinetic energy of impact of colliding automobiles, and for the containment of forces exerted by soil or water. Highway barrier devices, for example, are intended to provide a continuous wall or barrier along the center line of a highway when laid end-to-end to absorb grazing blows from moving vehicles. One commonly used highway barrier is formed of pre-cast reinforced concrete, and is known as the “New Jersey” style barrier. Highway barriers of this type have a relatively wide base including side walls which extend vertically upwardly from the pavement a short distance, then angle inwardly and upwardly to a vertically extending top portion connected to the top wall of the barrier. This design is intended to contact and redirect the wheels of a vehicle in a direction toward the lane of traffic in which the vehicle was originally traveling, instead of the lane of opposing traffic. See U.S. Pat. No. 4,059,362.
One problem with highway barriers of the type described above is the high weight of reinforced concrete. A barrier having a typical length of twelve feet weighs about 2,800-3,200 pounds and requires special equipment to load, unload and handle on site. It has been estimated that for some road repairs up to 40 percent of the total cost is expended on acquiring, delivering and handling concrete barriers. Additionally, concrete barriers have little or no ability to absorb shock upon impact, and have a high friction factor. This increases the damage to vehicles which collide with such barriers, and can lead to serious injuries to passengers of the vehicle.
In an effort to reduce weight, facilitate handling and shipment, and provide improved absorption of impact forces, highway barriers have been designed which are formed of a hollow plastic container filled with water, sand or other ballast material such as disclosed in U.S. Pat. Nos. 4,681,302; 4,773,629; 4,846,306, 5,123,773 and 5,882,140. For example, the '302 patent discloses a barrier comprising a container having a top wall, a bottom wall, opposed side walls and opposed end walls interconnected to form a hollow interior which is filled with water, and having fittings for coupling one barrier to another to form a continuous wall. The container structure is formed of a resilient material which is deformable upon impact and capable of resuming its original shape after being struck. Traction spoiler channels are provided to reduce the area of potential impact and thus the tendency of the vehicle to climb the walls of the barrier and vault over it into the opposing lane of traffic.
The '629, '306, '773 and '140 patents noted above represent further advances in deformable highway barrier designs. The first two patents disclose barriers which comprise a longitudinally extending container made of semi-rigid plastic which is self-supporting, and has a predetermined shape which is maintained when filled with water, sand or other ballast material. Such devices are connected end-to-end by a key insertable within grooves formed in the end walls of adjacent barriers. Interconnected fill openings are provided which permit adjacent barriers to be filled with water or the like when laid end-to-end.
The '773 and '140 patents disclose additional improvements in barrier devices including side walls formed with higher curb reveals, a horizontally extending step and vertical indentations in order to assist in maintaining the structural integrity of the container, and to create internal baffles for dampening movement of water or other fluid within the container interior. Interlocking male and female coupling elements are formed on opposite end walls of the barrier to facilitate end-to-end connection thereof. Additionally, such barriers are provided with channels or openings to permit the insertion of the tines of a fork lift truck therein for easy handling of the barriers.
Despite the improvements in highway barrier designs noted above, some deficiencies nevertheless remain. One concern has been with the ability of a wall of barriers, e.g. individual barriers connected end-to-end, to withstand a direct impact by a speeding vehicle. It has been found that plastic barriers tend to separate from one another at their connections, and in some instances break apart in response to a vehicle impact. Although concrete barriers of the type described above also can break apart during a crash, they are more resistant to that than plastic barriers and there is a need for plastic barriers to demonstrate impact resistance capabilities which more closely approximates those of concrete barriers.